Sheet-metal tube



.E.K. OOAS.

SHEET MBTALTUBE'.

. (No Model.)

No. 379,937.. Patented Mam 27, 1388.

, 14- WT N59856:;

NVENTU Edward Kjjaa f9 mgm fan-{y N. PETERS Fbaimlillognpfnn Wuhinflo D. C.

UNITED STATES PATENT OFFICE.

EDWARD K. GOA S, OF PROVIDENCE, RHODE ISLAND, ASSIGN OR TO THE PROVIDENCE CYLINDER COMPANY, OF NASHUA, NEW HAMPSHIRE.

SH EET-M ETAL TUBE.

SPECIFICATION forming part of Letters Patent No. 379,937, dated March 27, 1888.

Application filed December 20, 1886. Serial No. 222,054. (No model.)

To all whom it may concern:

Be it known that I, EDWARD K. OoAs, of Providence, in the State of Rhode Island, have invented certain Improvements in. Sheet-Metal Cylinders, of which the following. taken in connection with the accompanying drawings, is a specification.

This invention relates to improvements in that class of cylinders which are composed of metal strips coiled into a tube. It is particularly an improvement on the invention described in Letters Patent of the United States, heretofore granted to me, numbered 285,576.

The main object of this invention is to give a smooth uniform outer surface to the cylinder, and, secondarily, to give increased strength thereto.

In the drawings, Figure 1 is a perspective view of a partially-formed cylinder and illustrates one mode of carrying out my invention. Fig. 2 is a longitudinal section of this cylinder on a larger scale than Fig. 1. Fig. 3 is a sectional view of a piece of the metal ribbon prepared for winding. Figs. 4. and 5 are modified forms of cylinders.

In the Letters Patent referred to above I have described a mode of making cylinders by coiling a ribbon of sheet metal with its edges close together to the form of a tube, then coiling upon this tube another ribbon, breaking joints with the first, and, finally, uniting the coils and the tubular-formed barrels together by solder. In carrying out that invention the edges of the metal were allowed to abut against each other, and experience proves it difficult to wind the metal strips with their edges abutting to each other closely,,and the difficulty is increased by the practical inability of cutting or trimming the metal to an absolutely straight edge. It generally happens, therefore, by rea son of improper trimming, coiling, or otherwise, that openings appear between theabutting edges of the metal, and these openings, although they become closed by solder during the operation of uniting the barrels together, tend, first, to limit the strength of the cylinder, and, second, to form a wearing-surface composed of two metals, solder and steel, and for many uses this is decidedly objectionable and unsatisfactory, and to obviate such difficulties and objections is the object of this invention. To this end I give the metal ribbon a beveled edge, a, and an obve rsely beveled edge, e, which may be done by grinding off the metal along the edges of the ribbon, as shown in Fig. 3 of the accompanying drawings. The ribbon thus prepared is next coiled spirally to the form of a tube. The two obverselybeveled edges of the metal are thus brought together and lapped one over the other and are united together by solder. A cylinder formed in this manner presents a smooth uniform outer surface and has strength sufficient for many purposes; but when exceptional strength is required a second ribbonof sheet metal may be coiled upon the first tube, the two being allowed to break joints with each other and the whole united together with solder, as more fully described in the Letters Patent referredto above. In such cases the ribbon last coiled is the only one that compasses the outer surface of the cylinder, and therefore it is immaterial in such cases, except for purposes of strength, whether the inner coils have their edges lapped or abutted together. Greater strength will be obtained, of course, when all edges are lapped, and therefore I prefer to form them in this manner, though in the drawings I have represented each of these three formations.

I claim- 1 The method hereinbefore described of making metal cylinders of two thicknesses,consisting in coiling the fi rst thickness into cylindrical form, then coiling the second thickness about the first, so as to break joints, the edges of the outer thickness beingbev'eled. to overlap,and, finally, uniting the edge of the outer coil by solder, substantially as described.

EDWARD. K. 'ooAs. 

